Pot users show drop in IQ from adolescence to adulthood

Fox News

While smoking marijuana is sometimes touted for its ability to dull pain,  research has emerged showing that it also significantly dulls the mind – especially in teenagers.

A new study of more than 1,000 children in New Zealand, following them from  birth to the age of 38, found that those who began using cannabis during their  adolescence showed a decrease in their general intellectual ability, as measured  by IQ tests, from childhood to adulthood.

A person’s IQ – or intelligence quotient – does not measure a person’s amount  of knowledge, but rather represents a person’s ability to comprehend concepts,  as well their capacity to process information.  Typically, IQ does not  change significantly over the course of a person’s life, unless as a result of  severe brain damage from trauma or disease.

Although previous research has found adolescent cannabis use to have an  effect on IQ, this is the first study to rule out pre-cannabis performance  explaining the results.  Researchers initially tested the participants at  the age of 13 – before they began using cannabis – ultimately comparing this IQ  to later tests throughout their adulthood.

While drug tests were not used in this study, detailed questionnaires given  to the participants at five different ages throughout their lives helped to  establish their marijuana use.

“We assessed cannabis use in two ways,” the study’s lead author Madeline  Meier, of the Department of Psychology and Neuroscience and Duke  Transdisciplinary Prevention Research Center at Duke University, Durham, told  FoxNews.com.  “At [various] ages, they were asked to go back and report for  that past year how frequently they used cannabis.  They were also given  diagnostic interviews, where we diagnosed cannabis dependence.  Dependence  generally reflects someone who has been using cannabis and experiencing health,  social and/or legal problems – but are still continuing to use.”

Each individual was categorized into one of various groups depending on their  cannabis use and dependence.  The two main groups the researchers focused  on were adult-onset cannabis users and adolescent-onset cannabis users.  Adolescent-onset was defined in two ways – dependence on cannabis before the age  of 18 or weekly cannabis use before 18.  Adult-onset was defined the same  way for after the age of 18.

Upon determining the age of cannabis-use onset, the researchers then analyzed  the participants’ various IQ tests to establish trends in intelligence over  time.  For adult-onset cannabis users, there was ultimately no change in  their IQ over time.  But individuals who started using cannabis between the  ages of 13 and 18 experienced an average IQ drop of eight points.

Not only did intelligence decrease, but the changes seemed to be permanent.   Quitting or toning down cannabis use did not help adolescent-onset  cannabis users to recover their lost IQ points.

According to Meier, an eight-point drop may sound small, but it can actually  be a significant decrease with lasting effects.

“Take an average person – an IQ of 100 puts them in the 50th percentile of  intelligence,” Meier said. “If this person loses eight IQ points, it drops them  down to the 29th percentile.  IQ is a strong determinate of a person’s  access to college education, getting a job, performance on the job, tendency to  develop heart disease.  So those individuals who lose IQ points may be  disadvantaged toward the most important aspects of life.”

While the results may be staggering, Meier said there is still much work to  be done.  The researchers did not determine how much cannabis a person  needs to use in order to impair intelligence, as well as the age range that is  most vulnerable.  However, Meier feels that future research should focus on  cannabis use during the onset of puberty – a crucial time for the brain’s  development.

Even though more information is needed to establish the exact effects of  marijuana on the developing mind, Meier noted it’s important for adults and  teenagers alike to have a better understanding of just what cannabis does to  their minds and bodies.

“[People] really need to be aware that cannabis isn’t harmless for  adolescents,” Meier said.  “2011 was the first year in which adolescents  smoked more marijuana than cigarettes.  They’re getting the message that  cigarettes are dangerous and that marijuana is not.  They need to  understand that it is not harmless.”

Read more: http://www.foxnews.com/health/2012/08/27/pot-users-show-drop-in-iq-from-adolescence-to-adulthood/#ixzz25E05LLos

One thought on “Pot users show drop in IQ from adolescence to adulthood

  1. It’s called DOPE for a reason.

    Now we know what that reason is.

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